Epoxy resin apply

[hyboats]

Have got mold ready, I want laminate tomorrow,plan is polyster gelcoat, tissue mat, chopped mat, cloth, then mat cloth. all hand laminate. I want to apply one coat epoxy resin barrier to antiwater, now I want to know which layer should apply epoxy ? on the tissue mat or on the last layer ?
Does epoxy bonds to gelcoat well ?

[Herman]

Forget the epoxy at this stage. Polyester does not bond to epoxy.

Use good quality gelcoat (ISO-NPG) and a good barriercoat (Vinylester) and osmosis should not be a problem. Alsso make sure there are no air bubbles at all, so do a good deal of work with a bubble buster.

If you insist on using epoxy, then apply it afterwards, after having sanded the complete hull (below waterline)

[gonzo]

You can use a vynilester gelcoat.

[tunnels]

If you have polyester gelcoat , apply the tissue and a chopped strand p matt and use Vinylester resin as a barrier coat/skin then carry on and build the rest of the boat with polyester resin .

Its important to catalyst at the correct ratio when you apply your gel coat and also with you do the tissue with the vinylester resin .Remember this is the skin that you want to protect the rest of the laminate in the boat hull .

If you are looking at wanting to protect the inner most surface simply light sand and roll a generous coat of waxed resin in the places that are not seen and use flow coat in places that are seen .
On most boats i make i use Peel ply on the inner last lay up ! This gives a nice smooth finish and after the peel ply has been ripped off a hand scuff and a flo coat applied with a mohair roller makes a really nice smooth finish that is durable and easy to clean and keep clean .

[Herman]

Vinylester gelcoats tend to yellow over time.

Another hint: Using a better quality curing agent gives better results as well. Syrgis carries a curing agent called MEC, which causes much less porosity then standard MEKP. Also the overall quality of the curing agent is important. (water content, salts content)

You can do a "styrene shake" test to see if there is water in your MEKP.

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Inner layup: using peelply als has the advantage that you can leave that on as long as possible. The peelply will protect the laminate from resin spills, dirt from traffic, etc. Where a bulkheas should be glued in, take a knife and score the peelply, you can now remove a strip of peelply easily. When finished start in the front, removing peelply, and immediately coat with topcoat or epoxy coat.